NEIEP Machine Room Maintenance (550) Practice Test

Solvents should be kept away from the commutator and brushes because those surfaces need to stay dry and clean for proper electrical contact. Solvents can dissolve or soften coatings and lubricants, leave residues that promote arcing or carbon tracking, and may wash away lubrication around the brush area. They’re also typically flammable, adding a safety hazard near live electrical parts. Grease, water, or just air would either contaminate the contact surface or cause corrosion or shorting, making solvents the practice to avoid near the commutator and brushes.